How To Use Two Classes Together in a Division

Sometimes a situation may arise to use more then on class in attribute.But how can we achieve this during CSS coding ? In CSS we are allowed to do it.

If we have two Classes as

1)

 class="slider" 

2)

 class="toggle" 

Then We can apply these as

 <a class="slider toggle">.........</a> 

The thing which is required is a Space between the classes we are using